linux-kernel - Re: Regression due to d98849aff879 (dma-direct: handle DMA_ATTR_NO_KERNEL

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Message-ID: <20190806154403.GA25050@lst.de>
Date:   Tue, 6 Aug 2019 17:44:03 +0200
From:   Christoph Hellwig <hch@....de>
To:     Lucas Stach <l.stach@...gutronix.de>
Cc:     Christoph Hellwig <hch@....de>,
        "Lendacky, Thomas" <Thomas.Lendacky@....com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Halil Pasic <pasic@...ux.ibm.com>
Subject: Re: Regression due to d98849aff879 (dma-direct: handle
 DMA_ATTR_NO_KERNEL_MAPPING in common code)

On Tue, Aug 06, 2019 at 04:06:58PM +0200, Lucas Stach wrote:
> 
> dma_direct_free_pages() then needs the same check, as otherwise the cpu
> address is treated as a cookie instead of a real address and the
> encryption needs to be re-enabled.

Ok, lets try this one instead:

--
>From 3a7aa9fe38a5eae5d879831b4f8c1032e735a0b6 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@....de>
Date: Tue, 6 Aug 2019 14:33:23 +0300
Subject: dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING

The new DMA_ATTR_NO_KERNEL_MAPPING needs to actually assign
a dma_addr to work.  Also skip it if the architecture needs
forced decryption handling, as that needs a kernel virtual
address.

Fixes: d98849aff879 (dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING in common code)
Signed-off-by: Christoph Hellwig <hch@....de>
---
 kernel/dma/direct.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 59bdceea3737..4c211c87a719 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -130,11 +130,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
 	if (!page)
 		return NULL;
 
-	if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
+	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
+	    !force_dma_unencrypted(dev)) {
 		/* remove any dirty cache lines on the kernel alias */
 		if (!PageHighMem(page))
 			arch_dma_prep_coherent(page, size);
 		/* return the page pointer as the opaque cookie */
+		*dma_handle = phys_to_dma(dev, page_to_phys(page));
 		return page;
 	}
 
@@ -178,7 +180,8 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
 {
 	unsigned int page_order = get_order(size);
 
-	if (attrs & DMA_ATTR_NO_KERNEL_MAPPING) {
+	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
+	    !force_dma_unencrypted(dev)) {
 		/* cpu_addr is a struct page cookie, not a kernel address */
 		__dma_direct_free_pages(dev, size, cpu_addr);
 		return;
-- 
2.20.1